/*
 * Copyright 2022 Deep Learning on Flink Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.flinkextended.flink.ml.tensorflow.data;

import org.flinkextended.flink.ml.cluster.node.MLContext;
import org.flinkextended.flink.ml.data.RecordReader;
import org.flinkextended.flink.ml.util.SpscOffHeapQueue;

import java.io.DataInputStream;
import java.io.IOException;

/** TFRecord format implementation of RecordReader. */
public class TFRecordReaderImpl implements RecordReader {
    private TFRecordReader recordReader;
    private final DataInputStream input;
    private boolean eof = false;

    public TFRecordReaderImpl(MLContext mlContext) {
        SpscOffHeapQueue.QueueInputStream in = mlContext.getInReader();
        input = new DataInputStream(in);
        recordReader = new TFRecordReader(input, true);
    }

    @Override
    public byte[] tryRead() throws IOException {
        if (input.available() > 0) {
            return read();
        }
        return null;
    }

    @Override
    public boolean isReachEOF() {
        return eof;
    }

    @Override
    public byte[] read() throws IOException {
        byte[] bytes = recordReader.read();
        if (null == bytes) {
            eof = true;
        }
        return bytes;
    }

    @Override
    public void close() throws IOException {}
}
